The manufacturing of semiconductor wafers is a highly automated process involving many steps and locations where a wafer is processed. In fact, the manufacturing can take place across different manufacturing buildings and different portions of a country or even in multiple countries. A wafer carrier or “wafer boat” has evolved that is often used to carry wafers during the manufacturing process. Such wafer carriers are configured to allow automated handling of the wafers at individual manufacturing locations and to protect the wafer from physical forces as well as electrical damage. A wafer will often be carried by the same wafer carrier between many steps of the manufacturing process, if not between all steps. At each processing step, the wafer is removed from the carrier and processed before being redeposited back in the wafer carrier.
Testing of wafers is now a significant percentage of the cost of semiconductor manufacturing. As circuits have become increasingly more sophisticated, the testing involved for such circuits has also increased. Furthermore, wafers are often manufactured with dense numbers of individual dies on a single wafer. Thus, a single wafer can hold multiple dies which each hold an individual circuit. Thus, multiple circuits are manufactured on a single wafer so that the wafer can later be divided into individual chips.
Due to the significant cost involved in producing semiconductor chips as well as the significant cost of testing such semiconductor chips, it would be beneficial if there were a way to reduce the amount of testing required on a chip when the manufacturing process is completed. Similarly, it would be beneficial if there were a way to identify early in a manufacturing process an effective manufacturing step that could be remedied before a wafer was completed. Moreover, it would be beneficial if there were a way to determine that repairable chips are defective while they are still in the manufacturing process so that the manufacturing yield could be improved for the overall process.